High fuel costs and a desire to reduce undesirable emissions associated with operation of internal combustion engines has renewed interest in improving fuel efficiency during operation. Thus, it may be desirable to improve the efficiency of conventional internal combustion engines.
A conventional internal combustion engine includes a cylinder block defining journals for receiving a crankshaft and one or more cylinders housing a piston that is operably coupled to the crankshaft at a crankpin via a connecting rod. During conventional operation, the piston reciprocates within the cylinder, such that during a power stroke of the internal combustion engine, combustion of an air/fuel mixture within a combustion chamber defined by the piston, the cylinder, and a cylinder head forces the piston toward the crankshaft. As the piston travels toward the crankshaft, the crankshaft is rotated via the connecting rod and crankpin, thereby converting the potential energy associated with the air/fuel mixture into mechanical work.
Due to the architecture of a conventional internal combustion engine, when the piston is at a position within the cylinder that coincides with the maximum compression (i.e., the combustion chamber is at its lowest volume when the piston is farthest from the crankshaft), the axis of the connecting rod and the axis of the crankpin tend to be nearly co-linear, if not co-linear. At these relative positions, as the piston first begins its movement toward the crankshaft during the power stroke, there is only a very short moment arm (if any) created between the axis of the connecting rod and the axis of the crankpin. As a result, the force initially created by the air/fuel mixture at the moment of combustion does not transfer as much torque to the crankshaft as it would if the length of the moment arm were greater. This situation may be particularly undesirable because during combustion and very shortly thereafter, the force on the piston due to the combustion event approaches its maximum magnitude. Further, as the piston travels down the cylinder toward the crankshaft and the length of the moment arm increases, the magnitude of the force from the combustion event acting on the piston dissipates rapidly. Thus, because there is a very short moment arm created between the axis of the connecting rod and the axis of the crankshaft during the time of maximum force on the piston, efficiency of the work generated from the combustion process may be less than desired.
Thus, it may be desirable to provide an internal combustion engine with a configuration that improves the efficiency of the internal combustion engine during operation. Further, it may be desirable to provide an internal combustion engine with a configuration that permits tailoring of desired performance characteristics.